Search Results (133)

This study presents the synthesis, physicochemical characterization, and biological evaluation of a novel ternary nickel(II) complex with isoleucine and 1,10-phenanthroline ligands, [Ni(Phen)(Ile)₂]∙6H₂O, designed as a potential antitumor agent. Single-crystal X-ray diffraction revealed a monoclinic structure (C2-space group) with an octahedral Ni(II) coordination involving Phen and Ile ligands. A Hirshfeld surface analysis highlighted intermolecular interactions stabilizing the crystal lattice, with hydrogen bonds (H···H and O···H/H···O) dominating (99.1% of contacts). Density functional theory (DFT) calculations, including solvation effects (in water and methanol), demonstrated strong agreement with the experimental geometric parameters and revealed higher affinity to the water solvent. The electronic properties of the complex, such as HOMO−LUMO gaps (3.20–4.26 eV) and electrophilicity (4.54–5.88 eV), indicated a charge-transfer potential suitable for biological applications through interactions with biomolecules. Raman and infrared spectroscopic studies showed vibrational modes associated with Ni–N/O bonds and ligand-specific deformations, with solvation-induced shifts observed. A study using ultraviolet–visible–near-infrared absorption spectroscopy demonstrated that the complex remains stable in solution. In vitro cytotoxicity assays against MCF-7 (breast adenocarcinoma) and HCT-116 (colorectal carcinoma) cells showed dose-dependent activity, achieving 47.6% and 65.3% viability reduction at 100 μM (48 h), respectively, with lower toxicity to non-tumor lung fibroblasts (GM07492A, 39.8%). Supporting the experimental data, we performed computational modeling to examine the pharmacokinetic profile, with particular focus on the absorption, distribution, metabolism, and excretion properties and drug-likeness potential. Full article

Background/Objectives: Melanoma is one of the most aggressive forms of skin cancer and is frequently associated with the B-Raf⁶⁰⁰E mutation, which constitutively activates the MAPK signaling pathway. Although selective inhibitors such as Vemurafenib offer clinical benefits, their long-term efficacy is often hindered by resistance mechanisms and adverse effects. In this study, twelve phytochemicals from Brazilian green propolis were evaluated for their potential as selective B-Raf⁶⁰⁰E inhibitors using a computational approach. Methods: Physicochemical, ADME, and electronic properties were assessed, followed by molecular docking using the B-Raf⁶⁰⁰E crystal structure (PDB ID: 3OG7). Redocking validation and 500 ns molecular dynamics simulations were performed to investigate the stability of the ligand-protein complexes, and free energy calculations were then computed. Results: Among the tested compounds, Artepillin C exhibited the strongest binding affinity (−8.17 kcal/mol) in docking and maintained stable interactions with key catalytic residues throughout the simulation, also presenting free energy of binding ΔG of −20.77 kcal/mol. HOMO-LUMO and electrostatic potential analyses further supported its reactivity and selectivity. Notably, Artepillin C remained bound within the ATP-binding site, mimicking several critical interactions observed with Vemurafenib. Results: Among the tested compounds, Artepillin C exhibited the strongest binding affinity (−8.17 kcal/mol) and maintained stable interactions with key catalytic residues throughout the simulation. HOMO-LUMO and electrostatic potential analyses further supported its reactivity and selectivity. Notably, Artepillin C remained bound within the ATP-binding site, mimicking several critical interactions observed with Vemurafenib. Conclusions: These findings indicate that Artepillin C is a promising natural compound for further development as a selective B-Raf⁶⁰⁰E inhibitor and suggest its potential utility in melanoma treatment strategies. This study reinforces the value of natural products as scaffolds for targeted drug design and supports continued experimental validation. Full article

This article discloses the synthesis of four new positional isomeric zwitterionic ligands exhibiting semi-flexible and flexible characteristics—n-pyridinium-1,2,3-triazole-4-carboxy-5-Acetate (n-PTCA), and n-methylpyridinium-1,2,3-triazole-4-carboxy-5-Acetate (n-MPTCA; where n = 3, 4)—which were derived from an aqueous solution of the corresponding sodium salts in an acidic medium (HCl). These compounds are successfully synthesized and characterized with FT-IR and multinuclear NMR spectroscopy; likewise, proper single crystals are obtained for each compound. All compounds adopt zwitterionic forms in the solid state, which are stabilized via intermolecular proton transfer processes involving HCl and solvent molecules. A single-crystal X-ray analysis revealed how positional isomerism and molecular flexibility influence the supramolecular topology. Specifically, 3-PTCA and 4-PTCA exhibit isomorphic hydrogen bond networks, while 3-MPTCA and 4-MPTCA display distinct packing motifs, attributed to the presence of a methylene spacer between the pyridinium and triazole rings. The Hirshfeld surface analysis quantitatively confirmed the dominance of O···H/H···O and N···H/H···N interactions in the solid-state architecture. These strong hydrogen-bonding networks are indicative of the potential proton-conductive behavior in the crystalline state, positioning these compounds as promising candidates for applications in proton-conducting materials. The structural insights gained underscore the pivotal role of molecular topology in tailoring crystal packing, with implications for the rational design of zwitterionic ligands in functional materials, including MOFs and coordination polymers. The calculated HOMO-LUMO energy gaps reveal a significant electronic variability among the ligands, influenced primarily by the positional isomerism and structural flexibility introduced by the methylene spacer. Full article

Background: Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder characterised by the accumulation of neurotoxic substances in the brain, ultimately leading to progressive cognitive decline. The complex aetiology and involvement of multiple molecular targets in AD pathogenesis have made discovering effective therapeutic agents particularly challenging. Targeting multiple proteins simultaneously with a single therapeutic agent may offer a promising strategy to address the disease’s multifaceted nature. Methods: This study employed advanced computational methodologies to perform multitargeted molecular docking of FDA-approved drugs against four key AD-associated proteins implicated in disease progression. Among the screened compounds, Rebamipide—a drug conventionally used for treating gastrointestinal disorders—demonstrated notable binding affinities across all targets. Pharmacokinetic predictions, interaction fingerprinting, WaterMap analysis, density functional theory (DFT) calculations, and 100 ns MD simulations were performed for each protein–ligand complex to evaluate its multitarget potential. Results: Rebamipide bound effectively to the NR1 ligand-binding core, suggesting modulation of glutamatergic signalling while reducing β-secretase production and regulating neurotransmitter homeostasis through inhibiting monoamine oxidase-A. Furthermore, Rebamipide enhanced cholinergic neurotransmission by inhibiting human acetylcholinesterase, potentially improving cognitive function. Pharmacokinetic analyses confirmed favourable drug-like properties. Molecular interaction fingerprints revealed consistent hydrogen bonding, hydrophobic contacts, and π-π stacking interactions. WaterMap analysis indicated thermodynamically favourable water displacement upon binding, enhancing ligand affinity. DFT analysis of Rebamipide showed a 4.24 eV HOMO-LUMO gap, with ESP values ranging from −6.63 × 10⁻² to +6.63 × 10⁻² A.U., indicating reactive sites. TDDFT predicted strong UV absorption at 314 nm with a peak intensity of ~6500 L mol⁻¹ cm⁻¹. MD simulations over 100 ns demonstrated minimal structural deviations and stable ligand–protein complexes, reinforcing its multitarget efficacy. Conclusions: The comprehensive in silico investigation highlights Rebamipide as a promising multitargeted therapeutic candidate for Alzheimer’s disease. Its ability to modulate multiple pathogenic pathways simultaneously underscores its potential utility; however, these computational findings warrant further experimental validation to confirm its efficacy and therapeutic relevance in AD. Full article

In the present work, we describe the use of the potentially tridentate ligand pyridine-2-amidoxime (NH₂paoH) in Fe-Co chemistry. The 1:1:3 Fe^III(NO₃)₃·9H₂O/Co^II(ClO₄)₂·6H₂O/NH₂paoH reaction mixture in MeOH gave complex [Co^III₂Fe^III(NH₂pao)₆](ClO₄)₂(NO₃) (1) in ca. 55% yield, the cobalt(II) being oxidized to cobalt(III) under the aerobic conditions. The same complex was isolated using cobalt(II) and iron(II) sources, the oxidation now taking place at both metal sites. The structure of 1 contains two structurally similar, crystallographically independent cations [Co^III₂Fe^III(NH₂pao)₆]³⁺ which are strictly linear by symmetry. The central high-spin Fe^III ion is connected to each of the terminal low-spin Co^III ions through the oximato groups of three 2.1110 (Harris notation) NH₂pao⁻ ligands, in such a way that the six O atoms are bonded to the octahedral Fe^III center ({Fe^IIIO₆} coordination sphere). Each terminal octahedral Co^III ions is bonded to six N atoms (three oximato, three 2-pyridyl) from three NH₂pao⁻ groups ({Co^IIIN₆} coordination sphere). The IR and Raman spectra of the complex are discussed in terms of the coordination mode of the organic ligand, and the non-coordinating nature of the inorganic ClO₄⁻ and NO₃⁻ counterions. The UV/VIS spectrum of the complex in EtOH shows the two spin-allowed d-d transitions of the low-spin 3d⁶ cobalt(III) and a charge-transfer NH₂pao⁻ → Fe^III band. The δ and ΔΕ_Q ⁵⁷Fe-Mössbauer parameter of 1 at 80 K show the presence of an isolated high-spin Fe^III center. Variable-temperature (1.8 K–300 K) and variable-field (0–7 T) magnetic studies confirm the isolated character of Fe^III. A critical discussion of the importance of NH₂paoH and its anionic forms (NH₂pao⁻, NHpao²⁻) in homo- and heterometallic chemistry is also attempted. Full article

Bis-(o-dipheylphosphinophenyl)amine, a tridentate (PNP) chelating ligand, and several of their Rare Earth (RE) metal complexes, [bis-(o-dipheylphosphinophenyl)amido]-RER₂, {[(C₆H₅)₂P-o-(C₆H₄)]₂NMR₂ (R = -CH₂-o-(C₆H₄)NMe₂: M = Y, 1; Nd, 2; Gd, 3;), are prepared in high yields. When activated with the strong Lewis acid MMAO-7, all these complexes exhibit catalytic activity toward the polymerization of isoprene (IP) in non-protic hydrocarbons. While the Nd complex (2) showed moderate activity and stereoselectivity, the Y and Gd complexes (1 and 3) exhibited extremely high catalytic efficiency in IP homo-polymerization, and produced polyisoprene rubber (PI) with 95% to over 99% cis-1,4 stereoselectivity and narrow polydispersity indices (<2.0). Moreover, under industrially relevant conditions, complex 3 can catalyze IP to produce ultrahigh molecular weight PI (UHMW-PI, MW up to 1200–2600 kg/mol) rubber with a very narrow polydispersity index (PDI ca. 1.1–1.6), a high-performance elastomeric material mimic of natural rubber (NR). Full article

Coordination-driven Cu(I) complexes constitute an interesting class of materials with rich opto-electronic properties and diverse applications. Various homo- and heteroleptic Cu(I) complexes have been reported in the literature. In continuation with our quest for new materials, we report herein two novel coordination-driven self-assembled Cu(I) complexes: the homoleptic (1) and the heteroleptic (2) complexes based on the 6,6′-bis(phenylethynyl)-2,2′-bipyridine (L1) and 2,9-dimethyl-1,10-phenanthroline (dmph) ligands. L1 was prepared by a Pd(II)-catalyzed Sonogashira cross-coupling reaction between phenylactylene and 6,6′-dibromo-2,2′-bipyridine. Homo- and heteroleptic Cu(I) complexes were obtained by the self-assembly of L1 and dmph ligands. Complexes (1) and (2) were obtained in high yields, and are soluble in common organic solvents and stable at room temperature over a long period of time. The optical (absorption and emission) properties of both complexes were evaluated. The optical properties in solution are a function of the ligands and varied for the complexes. Complex (2) was also characterized by single-crystal X-ray diffraction and the intermolecular interaction was studied using Hirschfeld surface analysis. In the solid state, complex (2) exhibited four-coordinate distorted tetrahedral geometry around Cu(I). Density functional theory (B3LYP/6-311++G(d,p) was utilised to determine various molecular descriptors. Full article

Chemically modified electrodes based on derivatives of 2-thioxothiazolidin-4-one were mentioned as possible solutions for heavy metal (HM) ions heterogeneous recognition. Such ligands form thin films with reversible responses in the ferrocene redox probe with a well-defined symmetrical peak and symmetrical values for the anodic and cathodic currents. Their selectivity in coordinating HM ions was proven. In this paper, a computer-added study was performed using density functional theory (DFT) based on two methods, B3LYP and ωB97XD, to arrive at a better inside of their structure. Properties related to their reactivity concerning experimental electrochemical behaviour and spectral results were calculated using specific molecular descriptors. DFT-calculated HOMO-LUMO energies were found in good linear correlation with experimental redox potential. The accuracy of the calculations was also proven by a good agreement between the energy calculated by the DFT method and the UV-Vis spectra for the studied ligands. Such a computational approach can be used to evaluate the properties of possible new ligands for such electrochemical applications. The strong correlation between DFT-predicted quantum parameters and experimental redox potentials underscores the relevance of these computational approaches in designing selective molecular sensors. The results obtained using the two functionals are in good agreement, although there are also situations and parameters for which the results are not identical. There is a symmetry of the values obtained by the electrochemical and spectral methods with those calculated by DFT. Full article

The widespread use of organic dyes in industrial processes has led to a considerable release of these compounds into water systems, making the removal of organic contaminants from freshwater a pressing challenge. Photocatalysis, particularly through coordination compounds, presents a promising solution to this problem. In this study, we report the synthesis and characterization of three novel dissymmetric bis(thiosemicarbazone) ligands and their corresponding nickel(II) complexes, which have been extensively analyzed using various techniques. We evaluated the photocatalytic degradation of methyl orange by these nickel complexes, with results demonstrating that they exhibit superior efficiency compared to previously reported nickel-based complexes. Theoretical calculations reveal a correlation between the HOMO–LUMO energy gap and the energies of the involved orbitals. Additionally, with the growing demand for sustainable fuels that do not contribute to greenhouse gas emissions, molecular hydrogen stands out as a promising candidate. Given the potential of bis(thiosemicarbazone) complexes for electrocatalytic hydrogen evolution, we performed preliminary experiments to assess the ability of these nickel complexes to function as photocatalysts for water splitting. The results show that the three nickel complexes successfully generate hydrogen under the tested conditions, although further optimization is necessary to improve hydrogen production efficiency. Full article

Background/Objectives: Helicobacter pylori infects approximately half of the global population, causing chronic gastritis, peptic ulcers, and gastric cancer, a leading cause of cancer mortality. While current therapies face challenges from rising antibiotic resistance, particularly to clarithromycin, alongside treatment complexity and costs, the World Health Organization has prioritized the development of new antibiotics to combat this high-risk pathogen. In this study, we employed computer-aided drug design (CADD) methodologies, including molecular docking, Molecular Mechanics-Generalized Born Surface Area (MM-GBSA) analysis, molecular dynamics (MD) simulations, and Density Functional Theory (DFT) calculations, to explore the potential repurposing of FDA-approved agents as inhibitors of Helicobacter pylori shikimate kinase (HpSK). Methods: Using the Glide module, the HTVS method was initially applied to screen 1615 FDA-approved agents followed by extra-precision (XP) docking for the obtained 111 hits. The obtained XP scores were used to confine the results to those hits with a score above the reference ligand, shikimate, score. This yielded 31 final hits with an XP score above −5.867. MM-GBSA calculations were performed on these top candidates and the reference ligand to refine the analysis and compounds’ prioritization. Results: The 31 compounds displayed binding free energy (ΔG_bind) values ranging from 3.61 to −55.92 kcal/mol, with shikimate exhibiting a ΔG_bind of −34.24 kcal/mol and 10 hits having a lower ΔG_bind value. Out of these ten, three drugs—Dolutegravir, Cangrelor, and Isavuconazonium—were selected for further analysis based on their drug-like properties. Robust and stable binding profiles for both Isavuconazonium and Cangrelor were verified via molecular dynamics simulation. Additionally, Density Functional Theory (DFT) analysis was conducted, and the Highest Occupied Molecular Orbitals (HOMOs), Lowest Unoccupied Molecular Orbitals (LUMOs), and the energy gap (HLG) between them were calculated. All three drug candidates displayed lower HLG values than shikimate, suggesting higher reactivity and more efficient electronic transitions than the reference ligand. Conclusions: These findings suggest that the identified drugs, although not optimal for direct repurposing, would serve as promising leads against Helicobacter pylori shikimate kinase. These drugs could be valuable leads for experimental assessment and further optimization, particularly with no prototype yet identified. In terms of potential for clinical repurposing, the results point to diflunisal as a promising candidate for further testing. Full article

The potential of semiconducting, corrugated graphene, grown on silicon carbide, as an active element in chemosensors is studied in the present work. For this purpose, the adsorption of benzene, diazepam and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the material’s surface was modeled. According to the graphene sheet bending and adsorbate–adsorbent distances, the heterostructure favors the ligands in the order of diazepam < benzene < TCDD. The apparent ambiguity in the results for diazepam is easy to explain. The abundance of lone pairs and π-electrons compensates for the low-symmetry, non-planar, far from optimal (adsorption-wise) geometry. The maximum band gap change in the heterostructure, caused by adsorption, is 0.02 eV. Intermolecular binding does not alter the HOMO–LUMO difference in benzene and TCDD by more than 0.01 eV. The completely planar molecules are not expected to undergo significant geometrical changes; hence, the alteration in their frontier orbitals is also minimal. The adsorption of diazepam, however, causes significant changes in the projected density of states of both structures in the complex. In conclusion, corrugated graphene is applicable as an active material in selective chemosensors for non-planar aromatic molecules. Full article

Lactopontin (LPN) is a highly phosphorylated O-glycosylated acidic protein closely associated with infant gut, brain, and immune development, and its recognition is urgent due to its rising application in fortified dairy products and infant formula. In this study, an ssDNA aptamer against LPN was obtained, among which two kinds of matrix-background-assisted systematic evolution of ligands via exponential enrichment (SELEX) approaches were performed and compared. The direct approach was to utilize the sample matrix as the mixing-incubation background between the ssDNA library and LPN that can theoretically increase screening pressure and simulate practical application scenarios. The indirect approach was to utilize a PBS buffer as a screening background and to include counter-screening steps that adopt the “sample matrix” as a whole as the counter-screening target. Their screening evolutions were monitored through qPCR assays from sequence diversity convergences of each sub-library based on the change in the proportion of hetero- and homo-duplexes from the dissociation curve and melting temperature, which were also verified from the sequence statistics of high-throughput sequencing. The common sequence of Seq.I1II3 from the two approaches was finally fished out as the aptamer through multiple analyses of combining the sequence frequency, secondary structures, homology, and binding assessments, which was demonstrated good specificity and low-nanomolar affinity by qPCR assay (K_D, 5.9 nM). In addition, molecular docking and a dynamics simulation were performed for their binding site prediction and affinity confirmation. This study provides a potential identifying element and a basis for accelerating the development of methods for LPN detection in dairy products. Full article

This structural study examines over 102 coordinate Cu(I) complexes with compositions such as C-Cu-Y (Y=HL, OL, NL, SL, SiL, BL, PL, Cl, Br, I, AlL, or SnL), N-Cu-Y (Y=OL, Cl), S-Cu-Y (Y=Cl, Br, I), P-Cu-Y (Y=Cl, I), and Se-Cu-Y (Y=Br, I). These complexes crystallize into three different crystal classes: monoclinic (seventy-two instances), triclinic (twenty-eight instances), and orthorhombic (eight instances). The Cu-L bond length increases with the covalent radius of the ligating atom. There are two possible geometries for coordination number two: linear and bent. A total of 21 varieties of inner coordination spheres exist, categorized into two hetero-types (C-Cu-Y, i.e., organometallic compounds and X-Cu-Y, i.e., coordination compounds). The structural parameters of hetero Cu(I) complexes were compared with trans-X-Cu (I)-X (homo) complexes and analyzed. The maximum deviations from linearity (180.0°) are, on average, 10.3° for Br-Cu(I)-Br, 16.6° for C-Cu(I)-Sn, and 35.5° for P-Cu(I)-I. These results indicate that ligand properties influence deviation from linearity, increasing in the order of hard < borderline < soft. Full article

Breast cancer progression is strongly influenced by estrogen receptor-α (ERα), a ligand-activated transcription factor that regulates hormone binding, DNA interaction, and transcriptional activation. ERα plays a key role in promoting cell proliferation in breast tissue, and its overexpression is associated with the advancement of breast cancer through estrogen-mediated signaling pathways. Targeting ERα is, therefore, a promising therapeutic strategy for breast cancer. However, there are currently no phytochemical-based drug candidates approved for effectively inhibiting breast cancer progression driven by elevated ERα expression. This study aims to identify phytochemical inhibitors from Croton bonplandianum against ERα using pharmacoinformatics approaches. Eighty-three bioactive compounds from C. bonplandianum were retrieved from the IMPPAT (Indian Medicinal Plants, Phytochemistry, and Therapeutics) database and screened through molecular docking for their binding affinity to ERα. The top candidates were further evaluated through molecular dynamics simulations, ADME analysis, toxicity assessment, and quantum mechanics-based DFT calculations. The thermodynamic properties and HOMO-LUMO energy gap values indicated that the selected compounds were both stable and active. Among them, 2,3-oxidosqualene (CID-5366020) and 5,8,11-eicosatriynoic acid, trimethylsilyl ester (CID-91696396) demonstrated the most potent inhibitory activity against ERα. These findings suggest that these compounds have significant potential as therapeutic agents for breast cancer treatment by targeting ERα. Full article

Cyclic trinuclear homo-metal complexes, [{Fe(L³⁺²Br)py}₃] (1) and [{Mn(L³⁺²Br)}₃(py)₂ MeOH] (2), along with a hetero-metal complex, [FeMn₂(L³⁺²H)₃(DMF)₃] (3), were synthesized using asymmetric ditopic ligands (H₃L³⁺²H: 2-(2-hydroxyphenyl)-6-ol-5-(salicylideneamino)benzoxazole, H₃L³⁺²Br: 2-(2-hydrox-5-bromoyphenyl)-6-ol-5-(5-bromosalicylideneamino)benzoxazole). The molecular structure of 1 is characterized by a tripod structure with three-fold symmetry, where an enantiomer pair forms a dimeric capsule with dimensions of approximately 3 × 1.6 × 1.6 nm³. Complexes 2 and 3, which lack three-fold symmetry, exhibit similar molecular structures to previously reported complexes with these ligands, but do not form a capsule structure. Magnetic measurements of 1–3 reveal the presence of significantly weak antiferromagnetic interactions between the metal ions. Full article